Intravital lectin perfusion analysis of vascular permeability in human micro- and macro- blood vessels

We previously applied intravital lectin perfusion in mouse models to elucid ate mechanisms underlying vascular permeability. The present work transfers this technique to human models, analysing vascular permeability in macro- and microvessels. Human vascular endothelial surface carbohydrate biochemis try differs significantly from its murine counterpart, lacking alpha -galac tosyl epitopes and expressing the L-fucose moiety in the glycocalyx; the po ly-N-lactosamine glycan backbone is common to all mammals. We examined exte nsively lectin binding specificities in sections and in vivo, and then appl ied the poly-N-lactosamine-specific lectin LEA and the L-fucose-specific le ctin UEA-I in human intravital perfusions. Transendothelial transport diffe red in macrovessels and microvessels. In microvessels of adult human fat ti ssue, rectal wall and rectal carcinomas, slow transendothelial transport by vesicles was followed by significant retention at the subendothelial basem ent membrane; paracellular passage was not observed. Passage time exceeded 1 h. Thus we found barrier mechanisms resembling those we described previou sly in murine tissues. In both adult and fetal macrovessels, the vena saphe na magna and the umbilical vein, respectively, rapid passage across the end othelial lining was observed, the tracer localising completely in the suben dothelial tissues within 15 min; vesicular transport was more rapid than in microvessels, and retention at the subendothelial basement membrane briefe r.